Persistent Currents Versus Phase Breaking in Mesoscopic Metallic Samples

Persistent currents in mesoscopic normal metal rings represent, even a decade after their first experimental observation, a challenge to both, theorists and experimentalists. After giving a brief review of the existing experimental and theoretical results, we concentrate on the (propsed) relationship of the size of the persistent current to the phase breaking rate. In particular, we consider effects induced by noise, scattering at two level systems, and magnetic impurities.